--- page_id: wsd-hmm-might-have-found-a-bug-in-the-lvs-b60748cb type: context-page schema_version: 1 template_id: discord-page template_version: template-0.1.0 title: "Thread: Hmm, _might_ have found a bug in the LVS" slug: wsd-hmm-might-have-found-a-bug-in-the-lvs-b60748cb route: /evidence/designing/project-template/threads/hmm-might-have-found-a-bug-in-the-lvs section: reference access: public summary: 7 Discord messages from ๐Ÿ“ - Designing/๐Ÿ“-project-template/threads/hmm-might-have-found-a-bug-in-the-lvs.md. status: published asset_base: . home_href: / md_url: /evidence/designing/project-template/threads/hmm-might-have-found-a-bug-in-the-lvs.md toc_enabled: true talk_enabled: false agent_view_enabled: true copy_buttons_enabled: true footer_enabled: true search_indexed: true tags: [discord, wafer-space, archive] last_updated: 2026-08-19 talk_url: /evidence/designing/project-template/threads/hmm-might-have-found-a-bug-in-the-lvs.talk.md talk_route: /evidence/designing/project-template/threads/hmm-might-have-found-a-bug-in-the-lvs/talk --- # Thread: Hmm, _might_ have found a bug in the LVS Category: **๐Ÿ“ - Designing** Parent channel: **#๐Ÿ“-project-template** Thread ID: `1503418680451792966` Messages: **7** ## message-1503449602022703346 **2026-05-11T17:31:57.865+00:00 โ€” Leo Moser (mole99) (@mole99)** - Message ID: `1503449602022703346` - Author ID: `323371864074485771` - Nickname: Leo Moser (mole99) - User name: mole99 - Type: `21` - Discord message: https://discord.com/channels/1361349522684510449/1503418680451792966/1503449602022703346 - Archive source: https://discord.wafer.space/wafer-space/%F0%9F%8F%97%EF%B8%8F%20-%20Designing/project-template/hmm-might-have-found-a-bug-in-the-lvs/2026-05/2026-05.json - Archive source: https://discord.wafer.space/wafer-space/%F0%9F%93%90%20-%20Designing/%F0%9F%93%9D-project-template/hmm-might-have-found-a-bug-in-the-lvs/2026-05/2026-05.json **Reply/reference** - https://discord.com/channels/1361349522684510449/1423348662318272592/1503418680451792966
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**Content** ```text ```
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--- ## message-1503449617964994681 **2026-05-11T17:32:01.666+00:00 โ€” Leo Moser (mole99) (@mole99)** - Message ID: `1503449617964994681` - Author ID: `323371864074485771` - Nickname: Leo Moser (mole99) - User name: mole99 - Type: `Default` - Discord message: https://discord.com/channels/1361349522684510449/1503418680451792966/1503449617964994681 - Archive source: https://discord.wafer.space/wafer-space/%F0%9F%8F%97%EF%B8%8F%20-%20Designing/project-template/hmm-might-have-found-a-bug-in-the-lvs/2026-05/2026-05.json - Archive source: https://discord.wafer.space/wafer-space/%F0%9F%93%90%20-%20Designing/%F0%9F%93%9D-project-template/hmm-might-have-found-a-bug-in-the-lvs/2026-05/2026-05.json **Content** ````text Thanks for the report! Yes, it really seems `diode_connections.lvs` is the only place where `nwell` is used for the connection to the devices. Everywhere else, i.e. `moscap_extraction.lvs/mos_extraction.lvs/mos_sab_extraction.lvs/res_extraction.lvs`, `nwell_con` is used. If you take a look at `general_derivations.lvs` you can see that `nwell_con` is defined as: ``` nwell_con = nwell.not(res_mk) ``` I think this is so that nwell resistors are correctly extracted. They are extracted as: ``` # NWELL logger.info('Extracting NWELL device') extract_devices(resistor_with_bulk('nwell', 1000, BResistor), { 'R' => nwell_res, 'C' => nwell_con, 'W' => sub }) ``` You can find a description about the extractor here: https://www.klayout.de/doc/manual/lvs_device_extractors.html Taking a look at the connectivity setup in `general_connections.lvs`, only `nwell_con` is connected to `ntap`: ``` # Inter-layer connect(lvpwell_con, ptap) connect(lvpwell_con, ptap_dw) connect(dnwell, ntap_dw) connect(nwell_con, ntap) connect(ptap, contact) ... ``` That's the reason why you get anonymous pins with just `nwell`. Long story short, I agree that `nwell_con` should be used :) ````
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--- ## message-1503449680325902488 **2026-05-11T17:32:16.534+00:00 โ€” Leo Moser (mole99) (@mole99)** - Message ID: `1503449680325902488` - Author ID: `323371864074485771` - Nickname: Leo Moser (mole99) - User name: mole99 - Type: `Default` - Discord message: https://discord.com/channels/1361349522684510449/1503418680451792966/1503449680325902488 - Archive source: https://discord.wafer.space/wafer-space/%F0%9F%8F%97%EF%B8%8F%20-%20Designing/project-template/hmm-might-have-found-a-bug-in-the-lvs/2026-05/2026-05.json - Archive source: https://discord.wafer.space/wafer-space/%F0%9F%93%90%20-%20Designing/%F0%9F%93%9D-project-template/hmm-might-have-found-a-bug-in-the-lvs/2026-05/2026-05.json **Content** ```text If you would like to be credited, you can open a PR in the upstream repo: https://github.com/fossi-foundation/globalfoundries-pdk-libs-gf180mcu_fd_pv Otherwise, I will do it for you. ```
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--- ## message-1503449828607397948 **2026-05-11T17:32:51.887+00:00 โ€” Leo Moser (mole99) (@mole99)** - Message ID: `1503449828607397948` - Author ID: `323371864074485771` - Nickname: Leo Moser (mole99) - User name: mole99 - Type: `Default` - Discord message: https://discord.com/channels/1361349522684510449/1503418680451792966/1503449828607397948 - Archive source: https://discord.wafer.space/wafer-space/%F0%9F%8F%97%EF%B8%8F%20-%20Designing/project-template/hmm-might-have-found-a-bug-in-the-lvs/2026-05/2026-05.json - Archive source: https://discord.wafer.space/wafer-space/%F0%9F%93%90%20-%20Designing/%F0%9F%93%9D-project-template/hmm-might-have-found-a-bug-in-the-lvs/2026-05/2026-05.json **Content** ```text You might want to use the LVS setup in this directory anyway, as @Clyde Laforge has made some important improvements around substrate cuts recently. We are working on creating a new open_pdks PDK, which will allow us to switch from the current wafer.space PDK fork. However, this probably won't happen until next week, as I'll be at Hackaday Europe this weekend :) ```
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--- ## message-1503452466698522664 **2026-05-11T17:43:20.857+00:00 โ€” BreakingTaps (@polyfractal)** - Message ID: `1503452466698522664` - Author ID: `384390069412429834` - Nickname: BreakingTaps - User name: polyfractal - Type: `Default` - Discord message: https://discord.com/channels/1361349522684510449/1503418680451792966/1503452466698522664 - Archive source: https://discord.wafer.space/wafer-space/%F0%9F%8F%97%EF%B8%8F%20-%20Designing/project-template/hmm-might-have-found-a-bug-in-the-lvs/2026-05/2026-05.json - Archive source: https://discord.wafer.space/wafer-space/%F0%9F%93%90%20-%20Designing/%F0%9F%93%9D-project-template/hmm-might-have-found-a-bug-in-the-lvs/2026-05/2026-05.json **Content** ```text Awesome, thanks for taking a look @Leo Moser (mole99)! No credit needed, probably easier/faster for you to make the fix than for me to cobble together a PR ๐Ÿ™‚ Will take a look at that LVS setup for my own experiments! and goodluck/have fun at hackaday conf ๐Ÿ™‚ ```
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--- ## message-1503456962321322015 **2026-05-11T18:01:12.697+00:00 โ€” Leo Moser (mole99) (@mole99)** - Message ID: `1503456962321322015` - Author ID: `323371864074485771` - Nickname: Leo Moser (mole99) - User name: mole99 - Type: `Default` - Discord message: https://discord.com/channels/1361349522684510449/1503418680451792966/1503456962321322015 - Archive source: https://discord.wafer.space/wafer-space/%F0%9F%8F%97%EF%B8%8F%20-%20Designing/project-template/hmm-might-have-found-a-bug-in-the-lvs/2026-05/2026-05.json - Archive source: https://discord.wafer.space/wafer-space/%F0%9F%93%90%20-%20Designing/%F0%9F%93%9D-project-template/hmm-might-have-found-a-bug-in-the-lvs/2026-05/2026-05.json **Content** ```text PR is up: https://github.com/fossi-foundation/globalfoundries-pdk-libs-gf180mcu_fd_pv/pull/20 Great, and thank you! ๐Ÿ˜ƒ ``` **Embeds** - Resolved media URL: https://github.com/fossi-foundation/globalfoundries-pdk-libs-gf180mcu_fd_pv/pull/20
Embeds data ```json [ { "color": "#1E2327", "description": "Discovered thanks to a report by Zachary.\ndiode_nw2ps_* used the wrong layer for the bulk connection. general_connections.lvs uses nwell_con to connect to ntap.", "fields": [], "images": [], "inlineEmojis": [], "timestamp": null, "title": "fix: diode_nw2ps_* connect to nwell_con by mole99 ยท Pull Request #...", "url": "https://github.com/fossi-foundation/globalfoundries-pdk-libs-gf180mcu_fd_pv/pull/20" } ] ```
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--- ## message-1503461422171164772 **2026-05-11T18:18:56.008+00:00 โ€” BreakingTaps (@polyfractal)** - Message ID: `1503461422171164772` - Author ID: `384390069412429834` - Nickname: BreakingTaps - User name: polyfractal - Type: `Default` - Discord message: https://discord.com/channels/1361349522684510449/1503418680451792966/1503461422171164772 - Archive source: https://discord.wafer.space/wafer-space/%F0%9F%8F%97%EF%B8%8F%20-%20Designing/project-template/hmm-might-have-found-a-bug-in-the-lvs/2026-05/2026-05.json - Archive source: https://discord.wafer.space/wafer-space/%F0%9F%93%90%20-%20Designing/%F0%9F%93%9D-project-template/hmm-might-have-found-a-bug-in-the-lvs/2026-05/2026-05.json **Content** ```text woo! ``` **Reactions** - Resolved media URL: https://discord.wafer.space/wafer-space/%F0%9F%8F%97%EF%B8%8F%20-%20Designing/project-template/hmm-might-have-found-a-bug-in-the-lvs/2026-05/2026-05_media/1f64c-7C820.svg - Resolved media URL: https://discord.wafer.space/wafer-space/%F0%9F%8F%97%EF%B8%8F%20-%20Designing/project-template/hmm-might-have-found-a-bug-in-the-lvs/2026-05/2026-05_media/3c7c17f3225f6e56f4dccd83f14383f2-73F83.png
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